The hotwire anemometer) A hot-wire anemometer is essentially a fine wire, usually made of platinum, which is heated electrically and inserted into a flowing fluid. The wire temperature, which is a function of the fluid temperature, fluid velocity, and the rate of heating, may be determined by measuring its electrical resistance. 

(a) A straight cylindrical wire 0.5 in. long and 0.01 in, in diameter is exposed to a stream of air at 70°F flowing past the wire at 100 ft/s. What must the rate of energy input be in watts to maintain the wire surface at 600°F? Neglect radiation as well as heat conduction along the wire. 

(b) It has been reported 2 that for a given fluid and wire at given fluid and wire temperatures (hence a given wire resistance) I² = B√v_∞ + C in which I is the current required to maintain the desired temperature, v_∞ is the velocity of the approaching fluid, and C is a constant. How well does this equation agree with the predictions of Eq. 14.4-7 or Eq. 14.4-8 for the fluid and wire of (a) over a fluid velocity range of 100 to 300 ft/s? What is the significance of the constant C in Eq. 14B.3-1?